This invention relates generally to means for detecting a change in the slope of a member relative to a reference such as the horizontal. Slope detectors of the type described, when mounted on an axle of a vehicle, have greatest application as a flat tire detector. More particularly, when combined with appropriate circuitry, a slope detecting device may be used to warn the operator of a vehicle that one of the tires thereof has gone soft or flat. In certain situations, particularly when the vehicle includes a trailer, such a device would be an important safety feature since a flat tire on a trailer may otherwise go unnoticed by the vehicle operator for some time.
In the past, various slope detecting devices have been used to indicate that a tire of a vehicle had gone flat. One such device incorporated a pool of mercury inside a housing. When the slope of the housing changed, in response to the deflation of a tire, for example, the mercury pool would shift inside the housing, covering a pair of electrical contacts disposed near the end thereof. The mercury would have the effect of electrically closing the contacts, which were typically coupled to alerting means such as a lamp, to indicate that the tire had gone flat.
Such slope detecting devices were not without certain drawbacks. For example, some of the slope detectors of the prior art generally responded to changes in slope only when a predetermined threshold was exceeded. Thus, a gradually deflating tire would ordinarily go undetected until it was completely flat.
Certain slope detecting devices of the prior art, when used as a flat tire detector, also suffered from the further drawback that they sometimes falsely indicated the circumstance of a flat tire. Thus, if a spurious change in slope occurred, such as when one of the tires of the vehicle hit a pothole, a false indication of a flat tire would be given. Such falsing, of course, is highly undesirable. Though detectors were designed to prevent falsing, they were relatively cumbersome and inexpedient.
It is thus a primary object of this invention to provide an improved device for detecting a change in slope of a member relative to a reference. As set forth above, such a device would have great application on a vehicle as a flat tire detector.
It is another object of this invention to provide an improved slope detector capable of producing a detecting signal corresponding to the change in slope of a member relative to a reference.
A further object of the invention is to provide an improved slope detector, of particular use on a vehicle as a flat tire detecting device, which does not falsely indicate the occurence of a flat tire due to spurious slope variations such as those which may result when a tire of the vehicle hits a pothole.
Other objects, features and advantages of the invention will become more apparent hereinafter.